JPH06200833A - Abnormality deciding device of exhaust gas recirculating device - Google Patents

Abstract

PURPOSE:To decide the abnormal condition of an EGR(exhaust gas recirculating) device without confounding with the other abnormality of the engine. CONSTITUTION:An ECU31 reads the throttle opening TA, the suction air amount Q, the engine rotation frequency NE, the cooling water temperature THW, and the like, depending on the detecting signals from sensors 15 to 18, 25, 26, and 30, and a status switch 29. And the CPU 31 decides whether it is in the EGR operating area or not from these read data, and calculates the basic ignition timings theta B1 and thetaB2 according to the deciding result. And the ECU 31 calculates log angle amounts thetaK1 and thetaK2 according to whether it is in the EGR operating area or not depending on the knock detecting signal from a knock sensor 27, in a KCS operating area. The ECU 31 decides an abnormal condition of an EGR device 20 from the difference of the log angle amounts thetaK1 and thetaK2 (= thetaK1-thetak2). Consequently, knocking generating causes other than the EGR device 20 are cancelled, and only the abnormal condition of the EGR device 20 is decided accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is provided in an internal combustion engine such as an automobile, and to reduce the concentration of NO _X in the exhaust gas by recirculating a part of exhaust gas from an internal combustion engine to an intake system The present invention relates to an exhaust gas recirculation device (EGR device), and more particularly to an abnormality determination device that determines whether or not the exhaust gas recirculation device is operating normally.

[0002]

2. Description of the Related Art Conventionally, as this type of technique, for example, the "diagnosis device for an exhaust gas recirculation device" disclosed in Japanese Patent Laid-Open No. 63-239351 is known. This diagnostic device detects knocking occurring in an engine of an automobile, for example, with a knock sensor, and detects the knocking occurrence frequency from the exhaust gas recirculation device (hereinafter referred to as E
It is intended to determine an abnormality of a GR device).

The diagnostic device will be described below. Usually, an engine is provided with an ignition timing control device (ESA) to obtain an optimum ignition timing. The ignition timing is set near the knock limit in order to efficiently convert the explosive combustion of fuel into the rotational force of the crankshaft. The ignition timing control device adjusts the ignition timing based on information from sensors provided in the engine, for example, the throttle opening TA, the intake air amount Q, the engine speed NE, the cooling water temperature THW, etc. so that the ignition timing is near the knock limit. is doing.
The EGR device is activated when a condition preset as an EGR operation region is satisfied based on the information from each sensor. When the EGR device is operated, the exhaust gas recirculated to the intake system flows into the air-fuel mixture, so the knock limit shifts to the advance side. Therefore, the ignition timing control device is
Efficient ignition is performed by shifting the ignition timing in the GR operation region to the advance side by a predetermined angle amount with respect to the ignition timing in the EGR non-operation region.

However, if the exhaust gas is not recirculated to the intake system due to an abnormality in the EGR device or the flow rate of the recirculated exhaust gas is small, the knock limit is reached even though the exhaust gas is in the EGR operation range. It will not be sufficiently shifted and ignition will occur in the knocking area. As a result, knocking occurs. In the case of this diagnosis device, the knock sensor detects knocking occurring in this EGR operation region, and when the number of occurrences of knocking reaches a predetermined number, it is determined that the EGR device is abnormal.

[0005]

However, the occurrence of knocking is not determined only by the flow rate of the exhaust gas recirculated to the intake system, but other factors such as gasoline properties, air-fuel ratio, deposit accumulation in the combustion chamber, etc. It is also caused by the quantity and the temperature of the mixture injected into the combustion chamber. That is, when the octane number of gasoline is low, when the air-fuel ratio is lean (lean), when the deposit amount in the combustion chamber is large, and when the intake air temperature and the cooling water temperature are high, knocking is likely to occur.

Therefore, when it is attempted to judge the abnormality of the EGR device only by the number of knocking occurrences in the EGR operation region like the conventional diagnosis device, the EGR device is not activated due to other factors even if the EGR device is normal. There was a possibility that it would be erroneously determined to be abnormal. That is, when knocking occurs due to gasoline properties, fuel supply device abnormality, engine operating state change over time, vehicle running state, operating environment conditions, etc., even if the EGR device is operating normally, There was a risk of being erroneously determined to be abnormal.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is not to be confused with other abnormalities of the engine, and to make it possible to accurately determine only the abnormality of the EGR device. An object is to provide an abnormality determination device for a recirculation device.

[0008]

In order to solve the above problems, the present invention detects, as shown in FIG. 1, whether or not the exhaust gas recirculation system is in the exhaust gas recirculation operation range. Exhaust gas recirculation operation range detection means M1, ignition timing control means M2 that sets ignition timing depending on whether it is in the exhaust gas recirculation operation range, and knock detection means M3 that detects occurrence of knocking of the internal combustion engine. And the knock detection means M3
Retardation amount calculating means M4 for calculating the retardation amount with respect to the ignition timing when knocking is detected, and the retardation amount in the exhaust gas recirculation operation region and the retardation amount when not in the exhaust gas recirculation operation region. And a determination means M5 for determining abnormality of the exhaust gas recirculation device by comparing

[0009]

Therefore, according to the present invention, the exhaust gas recirculation operation range detecting means M1 detects whether or not it is in the exhaust gas recirculation operation range. The ignition timing control means M2 sets an appropriate ignition timing depending on whether or not it is in the exhaust gas recirculation operation range. Further, the knock detection means M3 detects the occurrence of knocking of the internal combustion engine, and when the knock detection means M3 detects knocking, the retard angle amount calculation means M4 causes the ignition until the knock detection means M3 stops detecting knocking. Calculate the amount of retard for the time.

Here, if the exhaust gas recirculation is not performed or the exhaust gas recirculation flow rate is low in the exhaust gas recirculation operation region due to an abnormality of the exhaust gas recirculation device, the ignition timing control means is provided. As a result, the ignition timing set by M2 is shifted to the knocking region side (advance value does not change). As a result, the retard amount in the exhaust gas recirculation operation region by the retard amount control means M4 becomes larger than the retard amount in the exhaust gas recirculation operation region. The determination means M5 determines the abnormality of the exhaust gas recirculation device from the difference between these two retard amounts. By taking the difference between the two retard amounts at the time of determination in this way, other factors,
For example, erroneous determination factors such as gasoline properties, air-fuel ratio, deposit amount in the combustion chamber, mixture temperature, etc. are canceled. Therefore, only the abnormality of the exhaust gas recirculation device is reliably determined. The difference between the two retard amounts used for the determination is obtained as the difference or ratio between the two retard amounts.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of an automobile multi-cylinder engine 1 as an internal combustion engine equipped with an EGR device. The engine 1 includes a piston 3 in a cylinder 2, and a combustion chamber 4 formed above the piston 3 communicates with an intake passage 5 and an exhaust passage 6. An intake valve 7 and an exhaust valve 8 open and close a communication portion between the combustion chamber 4 and the intake passage 5, and a communication portion between the combustion chamber 4 and the exhaust passage 6.

In the engine 1, a mixture of intake air from the intake passage 5 and fuel injected from a fuel injection injector 9 is passed through an intake valve 7 to a combustion chamber 4
Install inside. The engine 1 is equipped with a spark plug 10, and the spark plug 10 has a distributor 1
The ignition voltage distributed at 1 is applied. The distributor 11 outputs the high voltage output from the igniter 12,
It is for distributing to each spark plug 10 in synchronization with the crank angle of the engine 1, and the ignition timing of each spark plug 10 is determined by the high voltage output timing from the igniter 12. And the engine 1 has a spark plug 1
At 0, the air-fuel mixture is exploded in the combustion chamber 4 to obtain a driving force, and the exhaust gas is discharged to the exhaust passage through the exhaust valve 8.

A surge tank 13 for suppressing pulsation of intake air is provided in a part of the intake passage 5. On the upstream side of the surge tank 13, a throttle valve 14 that is opened and closed in conjunction with the operation of an accelerator pedal (not shown)
Is provided, and the intake air amount of the intake passage 5 is adjusted by opening / closing the throttle valve 14. A throttle sensor 15 that detects the opening degree is provided near the throttle valve 14. Throttle sensor 15
Has a movable contact that moves according to the opening of the throttle valve 14. The movable contact comes into contact with the idle contact near the time when the throttle valve 14 is fully closed. An air flow meter 16 for detecting the amount of intake air is provided upstream of the throttle valve 14.
And an air cleaner AC. An intake air temperature sensor 17 for detecting the temperature of the air taken into the intake passage 5, that is, the intake air temperature THA is provided between the air flow meter 16 and the air cleaner AC.

On the other hand, an oxygen sensor 18 for detecting the oxygen concentration in the exhaust gas and a three-way catalytic converter 19 for purifying the exhaust gas are attached to the exhaust passage 6. Further, the exhaust passage 6 is provided with an EGR device 20 for returning exhaust gas to the intake passage 5 for exhaust gas recirculation. That is, the EGR pipe 21 branches from the exhaust passage 6 and is connected to the intake passage 5 between the surge tank 13 and the throttle valve 14. An EGR valve 22 is arranged in the middle of the EGR pipe 21, and the EGR valve 22 adjusts the flow rate of exhaust gas recirculating in the EGR pipe 21 by opening and closing a valve body 24 driven by a step motor 23.

Further, in the engine 1, a rotation speed sensor 25 for detecting the rotation speed of the engine 1 from the rotation of the rotor 11a of the distributor 11, a water temperature sensor 26 for detecting the cooling water temperature of the engine 1, and a mechanical vibration of the engine 1. A knock sensor 27 that constitutes knock detection means for detecting the occurrence of knocking is attached. The knock sensor 27 is composed of a piezoelectric element having a resonance frequency of 6 to 8 kHz generated by knocking. Also, engine 1
Is provided with a starter 28 for starting the engine 1 by cranking, and the starter 28 is provided with a starter switch 29 for detecting that the engine 1 is being cranked. Further, a vehicle speed sensor 30 for detecting a vehicle speed is attached to a transmission (not shown) drivingly connected to the engine 1.

The above-mentioned throttle sensor 15, air flow meter 16, intake air temperature sensor 17, oxygen sensor 18, rotation speed sensor 25, water temperature sensor 26, knock sensor 27,
The starter switch 29 and the vehicle speed sensor 30 are electrically connected to the input side of an electronic control unit (hereinafter, simply referred to as “ECU”) 31. Further, each injector 9, igniter 12, and EGR valve 22 are electrically connected to the output side of the ECU 31, and the drive timing of these is controlled by the operation of the ECU 31. The ECU 31 constitutes an exhaust gas recirculation operation range detection means, an ignition timing control means, a knock detection means, a retard angle control means and a determination means.

Here, the electrical configuration of the ECU 31 will be described with reference to the block diagram of FIG. The ECU 31 includes a central processing unit (hereinafter referred to as a CPU) 32, a read-only memory (hereinafter referred to as a ROM) 33, a dumbram access memory (hereinafter referred to as a RAM) 34, a backup RAM 35, a timer counter 36, and the like, these units, an input port 37, and an output port. It is configured as a theoretical operation circuit in which 38 and the like are connected by a bus 39. CPU 32 is a ROM in advance
Various arithmetic processes are executed according to a predetermined control program stored in 33. The ROM 33 stores in advance control programs such as a fuel injection amount control routine and a basic ignition timing calculation routine, in addition to an "execution ignition timing calculation routine" and an "EGR abnormality determination routine" described later. Also, R
The AM 34 temporarily stores the calculation result of the CPU 32, and the backup RAM 35 stores and saves the data. The timer counter 36 outputs an interrupt signal at every predetermined time and simultaneously performs a plurality of counting operations.

The external input circuit 37 of the ECU 31 includes
The above-mentioned throttle sensor 15 and air flow meter 1
6, an intake air temperature sensor 17, an oxygen sensor 18, a rotation speed sensor 25, a water temperature sensor 26, a knock sensor 27, a vehicle speed sensor 30, a starter switch 29, etc. are connected to each other. Further, the external output circuit 38 includes the injectors 9,
The igniter 12, the EGR valve 22, and the indicator lamp 40 are connected. The indicator lamp 40 is turned on when an abnormality of the EGR device 20 is detected in the "SGR abnormality determination routine", and is turned off when the ignition is turned off.

The ECU 31 includes sensors 15 to 18 and 25 to
The throttle opening TA, the intake air amount Q, and the intake air temperature T based on the output signals from 27, 30 and the starter switch 29.
HA, oxygen concentration in exhaust gas, engine speed NE, cooling water temperature THW, vehicle speed SP, etc. are calculated. Then, each of the calculated data is read and the above-mentioned various control programs are executed to suitably drive and control each injector 9, igniter 12, and EGR valve 22. Thus, the fuel injection amount control of the engine 1, the ignition timing control, the KCS (knock control system) control and the E
GR control is performed.

That is, in the fuel injection amount control, the EC
U31 is throttle opening TA, intake air amount Q, intake air temperature T
The target fuel injection amount is calculated by reading HA, the oxygen concentration in the exhaust gas, the engine speed NE, the cooling water temperature THW, the vehicle speed SP, etc., and executing the fuel injection amount control routine. Then, the ECU 31 controls the valve opening of each injector 9 based on the valve opening time signal corresponding to the target fuel injection amount.

In the ignition timing control, the ECU 31
Is the throttle opening TA, intake air amount Q, intake air temperature THA,
The oxygen concentration OX in the exhaust gas, the engine speed NE, the cooling water temperature THW, the vehicle speed SP, the starter operating state, etc. are read. Then, the basic ignition timing θB is calculated by executing a basic ignition timing calculation routine based on the read data. The ECU 31 determines the basic ignition timing θB
The ignition instruction (IGt) signal is output before a predetermined angle amount (for example, 24 °) of the above, and the igniter 12 is caused to output a high voltage. The ignition timing of the ignition plug 10 is determined by the high voltage output timing from the igniter 12.

In KCS control, the ECU 31 detects the occurrence of knocking based on the knock detection signal from the knock sensor 27, reads the detection data, and executes the "execution ignition timing calculation routine". Then, the ECU 31 calculates the retard angle amount θK with respect to the basic ignition timing θB, and adds the correction amount of the retard angle amount θK to the basic ignition timing θB.
To set. Thus, in the KCS control, the output is improved, the fuel consumption is reduced, and the drivability is improved by setting the ignition timing near the knock limit. This KCS control is executed in a preset KCS operation area.

Further, the ECU 31 determines the operating state of the engine 1 based on the read data such as the throttle opening TA, the intake air amount Q, the engine speed NE, the cooling water temperature THW, etc. in the exhaust gas recirculation operating region (hereinafter referred to as “EGR”). It is referred to as an "operating area"). This EGR operating range is set to a wide range excluding the low load state and the extremely high load state of the engine 1. Here, the following items can be cited as examples of conditions that are determined not to be in the EGR operation range. The cooling water temperature THW is lower than a predetermined temperature (53 ° C), the engine is idling, the predetermined time (3 seconds) has not elapsed since the engine was started, and the racing (increases the engine speed NE under no load) It's time. Then, when it is determined that the EGR operation range is set, the ECU 31 opens the EGR valve 22. In this way, a part of the exhaust gas is returned to the intake system to reduce NO _{X in} the exhaust gas.

The basic ignition timing θB is equal to the EGR.
It is set in consideration of whether it is in the operating region. That is, the basic ignition timing θB in the EGR operation range
(Hereinafter referred to as θB1) is more predetermined than the basic ignition timing θB (hereinafter referred to as θB2) when the throttle opening TA, the intake air amount Q, the engine speed NE, etc. are not in the EGR operation range. The angle amount is set to the advance side. Thus, even if the EGR device 20 is operated and exhaust gas is recirculated to the intake system, a suitable basic ignition timing θB is always set.

Next, the processing operation and action of the abnormality determining device of the EGR device 20 equipped in the automobile multi-cylinder engine 1 configured as described above will be described with reference to the flowchart of FIG.

Here, the ECU 31 is started at the same time when the ignition is turned on, and the RAM 34 is started at the same time as the start.
And EGR abnormality flag FEGRFAIL and EGR operation determination flag FEG preset in the backup RAM 35
The R, KCS operation determination flag FKCS and the knocking determination flag FKNOCK are cleared. Further, the initial values θK = 0, θK1 = 0, θK2 = for the KCS retardation amount θK, the EGR operation region retardation amount θK1 and the EGR non-operation region retardation amount θK2, respectively.
0 is set. After that, the ECU 31 appropriately and repeatedly executes the "KCS control routine" and the "EGR abnormality determination routine" together with the fuel injection amount control routine and the ignition timing control routine.

The ECU 31 includes sensors 15-18, 25,
The throttle opening TA, the intake air amount Q, the intake air temperature THA, the oxygen concentration OX in the exhaust gas, the engine speed NE, and the cooling water temperature THW which are set with time based on the signals from the control switch 26, 30 and the starter switch 29. , Data such as vehicle speed SP and starter operating state are read. Then, the ECU 31 determines from the read data whether or not it is in the EGR operation region, and when it is in the EGR operation region, sets the EGR operation determination flag FEGR to "1",
When it is not in the EGR operation range, the EGR operation determination flag F
Clear EGR to "0".

Further, the ECU 31 also judges from the read data whether or not it is in the KCS operation region, and when it is in the KCS operation region, sets the KCS operation determination flag FKCS to "1".
If it is not in the KCS operation range, the KCS operation determination flag FKCS is cleared to "0". And K
In the CS operation area, the ECU 31 controls the knock sensor 27.
If the knock detection signal is input from, the knocking determination flag FKNOCK is set to "1", and if the knock detection signal is not input, the knocking determination flag FKNOCK is set.
Clear CK to "0".

FIG. 4 is a flow chart for explaining the "execution ignition timing calculation routine" executed by the ECU 31, and the routine is executed by a regular interruption every predetermined time.

When the processing shifts to this routine, first, at step 101, the EGR operation determination flag FEGR
Is "1". That is, it is determined whether or not it is in the EGR operation range. If the EGR operation determination flag FEGR is "0", it is determined that the EGR operation range is not set, and the basic ignition timing θB is determined in step 102.
Is set to the basic ignition timing θB2 when it is not in the EGR operation range. Further, when the EGR operation determination flag FEGR is "1", the EGR operation area is set, and in step 103, the basic ignition timing θB is set to the basic ignition timing θB1 when the EGR operation area is set.

Next, at step 104, it is judged if the knocking judgment flag FKNOCK is "1", that is, if the knock detection signal is inputted.
If the knocking determination flag FKNOCK is "1", it is determined that the knocking detection signal is input, and the routine proceeds to step 105. In step 105, the knocking strength is determined based on the knock detection signal, and the retard correction amount α1 is calculated from the determination result.

This retardation correction amount α1 is a preset value, and when knocking occurs repeatedly, this retardation correction amount α1 is the retardation amount θ at the time of preprocessing each time processing is performed.
By accumulating in K, the retard amount θ K of this processing is calculated. That is, the retard correction amount α1 is added to the original retard amount θK.
The value (= θK + α1) added with is set as a new retardation amount θK. Then, this retardation amount θK is temporarily stored in the RAM 34. After this processing, the process proceeds to step 109.

On the other hand, in step 104, when the knocking determination flag FKNOCK is "0", it is determined that the knock detection signal is not input, that is, knocking does not occur, and the routine proceeds to step 106.
In step 106, the retard angle correction amount α2 is added to the original retard angle amount θK.
The value obtained by subtracting (= θK−α2) is set as the new retardation amount θK. Then, this retardation amount θK is temporarily stored in the RAM 34.

This retard correction amount α2 is a preset value, and when knocking does not occur, the execution ignition timing θ is advanced by α2 compared to the pre-treatment. After this process, the process proceeds to step 107.

Then, in step 107, it is judged whether or not the retard amount θK is 0 or more. When the retard amount θK is 0 or more, the process directly proceeds to step 109, and when the retard amount θK is a negative value, the retard amount θK is set to “0” in step 108 and then the process proceeds to step 109. To do. This step 107 and step 108 are the retard angle θ.
This is a guard process that prevents K from becoming a negative value.

Next, at step 109, the execution ignition timing θ is calculated. That is, the basic ignition timing θB (= θB1, θB2) obtained in step 102 or 103
And the retard amount θK obtained in step 105 or step 106, the execution ignition timing θ (= θB−θK) is obtained.

The execution ignition timing θ thus obtained sets the ignition timing near the knock limit to improve the output, reduce the fuel consumption and improve the drivability. On the other hand, the ECU 31
Executes the EGR abnormality determination routine as shown in FIG. 5 together with the execution ignition timing calculation routine. The routine is designed to be executed by a regular interrupt every predetermined time.

When the processing shifts to this routine, first, at step 201, the KCS operation determination flag FKCS.
Is "1". That is, it is determined whether or not it is in the KCS operating region. When the KCS operation determination flag FKCS is “0”, it is determined that the KCS operation area is not set, and the EGR abnormality determination routine ends.

Next, in step 201, if the KCS operation determination flag FKCS is "1", the KCS
It is assumed that it is the operating region, and the process proceeds to step 202.
In step 202, the retardation amount θK is calculated. That is, the retard amount θK is determined by reading the latest retard amount θK obtained in step 105 or 106 in the execution ignition timing calculation routine from the RAM 34.

Next, at step 203, it is judged if the EGR operation determination flag FEGR is "1", that is, if it is in the EGR operation region. If the EGR operation determination flag FEGR is "1", it is determined that the EGR operation region is in effect, and the routine proceeds to step 204. In this step 204, the retard angle amount θK read in step 202 is set as the EGR operation retard angle amount θK1 in the RAM 3
Store in 4.

If the EGR operation determination flag FEGR is "0" in step 203, the EGR
When it is judged that it is not in the operating range, the routine proceeds to step 205. In step 205, the retard angle amount θK read in step 202 is set as the EGR non-operation retard angle amount θK2 in the RAM.
It stores in 34.

Then, in step 206, the RAM
The EGR operation retard angle amount θK1 and the EGR non-operation retard angle amount θK2 stored in 34 are read out, and the difference δ between the both retard angle amounts θK1 and θK2 is read.
Calculate (= θK1−θK2). After obtaining the difference δ, the process proceeds to step 207.

In step 207, the difference δ is the predetermined value K.
It is determined whether it is 1 or more. If the difference δ is less than the set value K1, the routine proceeds to step 208, and the EGR abnormality flag FEGRFAIL is cleared to "0". Also,
In step 207, when the difference δ is equal to or greater than the set value K1, the process proceeds to step 209, and the EGR abnormality flag FEGRFAIL is set to “1”.

In this way, the ECU 31 ends the processing of the "EGR abnormality determination routine". The set value K1 is E
This is a value calculated from a preliminary test assuming a failure of the GR valve 22.

Then, the ECU 31 determines that the EGR abnormality flag F
When the stored data of EGRFAIL is read, if the stored data is "0", nothing is done, and if it is "1", the indicator lamp 40 is turned on. The lighting of the indicator lamp 40 continues to be lit until the ignition is turned off, and this lighting causes E due to a failure of the EGR valve 22 or the like.
An abnormality of the GR device 20 is warned.

Therefore, according to the abnormality determining device of the EGR device 20, the basic ignition timing θB1 and the basic ignition timing θB2 are set according to whether the ignition control device is in the EGR operating region or not. To be done. Further, in the operating region of the KCS control, the knock sensor 27 detects knocking to calculate the correction amount for the basic ignition timings θB1 and θB2, and the execution ignition timing θ is controlled to be near the knock limit. .

Then, the EGR valve 2 is added to the EGR device 20.
When there is an abnormality due to a failure of No. 2 or the like and a part of the exhaust gas is not recirculated to the intake system or the flow rate of the recirculated exhaust gas is small, the actual knock limit is the EGR device 20.
It does not shift to the advance side as much as when normal. as a result,
The basic ignition timing θB1 set as the EGR operation range is
Since it belongs to the knocking region, knocking occurs during ignition. Then, the execution ignition timing θ by the KCS control is corrected to be larger than the basic ignition timing θB1 by the retard amount θK1. At this time, the retard amount θK1 is equal to the EGR
The value is larger than the retardation amount θK2 when not in the operating region.

On the other hand, the basic ignition timing θB2 when not in the EGR operation region is set near the actual knock limit regardless of the abnormality of the EGR device 20, so the retard angle amount θK2 by the KCS control is a relatively small value. Becomes Then, the abnormality determination device of the EGR device 20 of the present embodiment calculates the difference between the retard angle amount θK1 and the retard angle amount θK2 under the KCS control, and the difference δ (= θK1−θK2) becomes the set value K1 or more. Sometimes EG
It was determined that the R device 20 was abnormal.

Here, when knocking occurs due to, for example, the gasoline property, the air-fuel ratio, the amount of deposits in the combustion chamber, the temperature of the air-fuel mixture, etc., regardless of whether it is in the EGR operation region, the knocking occurs. The retardation amounts θK1 and θK2 are almost the same value (θK1 ≒ θK2). As a result, by taking the difference δ, these factors other than the abnormality of the EGR device 20 are almost certainly canceled. Therefore, unlike the conventional diagnosis apparatus, there is no risk of erroneously determining that the EGR device 20 is abnormal by detecting knocking caused by other factors, although the EGR device 20 is normal. Therefore, it is possible to reliably detect only the abnormality of the EGR device 20 due to the failure of the EGR valve 22 or the like.

As a result, the EGR device 20 can be repaired accurately and quickly. The malfunction of the EGR device 20 and the like are quickly repaired, so that it is possible to prevent deterioration of fuel consumption for a long time and air pollution due to NO _X emission. Further, since the abnormality determination of the EGR device 20 is performed by using the retard amount data from the KCS that controls the ignition timing,
There is a great cost advantage because there is no need to add a new system.

The present invention is not limited to the above-mentioned embodiments, but may be configured as follows, for example, within the scope of the invention. (1) In the above embodiment, the abnormality of the EGR device 20 is determined based on the difference δ between the retard angle amounts θK1 and θK2.
The EGR device 20 is configured to determine the ratio of θK2 (= θK1 / θK2) and determine whether the ratio is equal to or greater than a predetermined reference value.
The abnormality may be determined.

(2) In the above embodiment, the retard angle amounts θK1, θK1
The abnormality of the EGR device 20 is judged by the difference δ of
The number of knocking occurrences is counted according to whether or not it is in the EGR operation range, and the EG is calculated from the difference between the count values.
The abnormality of the R device 20 may be determined.

(3) The conditions for setting the EGR operating range are not limited to those in the above embodiment, but include information indicating the operating state of the engine 1 such as the throttle opening TA, the intake air amount Q, and the engine speed NE. Can be appropriately selected and set.

(4) In the engine 1 not subjected to KCS control, the knock sensor 27 may be mounted to determine the abnormality of the EGR device 20. (5) In the above embodiment, the retard angle amount θk in the EGR abnormality determination routine uses the retard angle amount θk obtained in the execution ignition timing calculation routine. However, the retard angle amount θk is independently obtained in the EGR abnormality determination routine. You can go.

[0055]

As described above in detail, according to the present invention, it is possible to accurately determine only the abnormality of the EGR device without being confused with other abnormality of the engine.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing an engine including an exhaust gas recirculation device in one embodiment.

FIG. 3 is a block diagram showing an electrical configuration of an ECU and the like in one embodiment.

FIG. 4 is a flowchart illustrating an “execution ignition timing calculation routine” executed by an ECU in one embodiment.

FIG. 5 is a flowchart illustrating an “EGR abnormality determination routine” executed by the ECU in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as internal combustion engine, 20 ... EGR device as exhaust gas recirculation device, 27 ... Knock sensor constituting knock detection means, 31 ... Exhaust gas recirculation device, ignition timing control means, knock detection means, retard angle ECU constituting amount calculation means, determination means, θB ... Basic ignition timing as ignition timing, θK ... KCS retardation amount as retardation amount, θK1 ... Retardation amount in exhaust gas recirculation operation range, θK2 ... Amount of retard angle when not in the exhaust gas recirculation operation range.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area F02P 5/15 G

Claims (1)

[Claims] 1. An exhaust gas recirculation operating region detecting means for detecting whether the exhaust gas recirculating device is in an exhaust gas recirculating operating region, and whether the exhaust gas recirculating operating region is in an exhaust gas recirculating operating region. Ignition timing control means for setting ignition timing in response, knock detection means for detecting the occurrence of knocking of the internal combustion engine, and retard angle for calculating the retard amount with respect to the ignition timing when the knock detection means detects knock. The exhaust gas recirculation operation range and the retardation amount when the exhaust gas recirculation operation range is not compared with the retardation amount when the exhaust gas recirculation operation range is not included. Exhaust gas recirculation device abnormality determination device.